PNO-V-85-047, on 850721-22,interference Problem W/Upper Lateral Support Bumper Block Assemblies on Steam Generators Identified.Originally Discovered During Hot Functional Testing in Late 1984.Bumper Installation Modified

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PNO-V-85-047:on 850721-22,interference Problem W/Upper Lateral Support Bumper Block Assemblies on Steam Generators Identified.Originally Discovered During Hot Functional Testing in Late 1984.Bumper Installation Modified
ML20132C406
Person / Time
Site: Diablo Canyon Pacific Gas & Electric icon.png
Issue date: 07/25/1985
From: Dodds R, Mendonca M
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-85-047, PNO-V-85-47, NUDOCS 8507300255
Download: ML20132C406 (1)


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(}V. /< l PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-85-47 Date: 07/25/85 This preliminary notification constitutes EARLY' notice of events of POSSIBLE safety or public intorest significance. The information presented is as initially received without verification er svaluation and is basically all that is known by Region V staff on this date.

FACILITY: Pacific Cas and Electric Company Licensee Emergency Classification Diablo Canyon Unit 2 Notification of Unusual Event Docket No. 50-323 Alert Site Area Emergency General Emergency

__XX_,Not Applicable

SUBJECT:

HEATUP SEQUENCE IN PREPARATION FOR CRITICALITY INTERRUPTED On July 21-22, 1985, during the verification of restraint clearance as part of the planned th rmal expansion monitoring program, the licensee identified an interference problem with thm upper lateral support bumper block assemblies on Unit 2 steam generators, 2-1 and 2-2, th:t has delayed the startup program for several days. The interference would not have ellowed sufficient clearance between the block key / keyway assembly to accommodate the th:rmal growth anticipated during heatup to normal temperature. The upper lateral supports aro designed primarily to limit steam generator movement under pipe break and seismic conditions.

Thio fu a continuation of an interference problem that was identified during hot functional testing in late 1984, at which time the bumper block faces were removed for machining.

Vsrification of cicarance following replacement was planned to be accomplished during the current heatup cycle. The exact cause of the current problem has not been identified.

Ilow ver, the licensee and Westinghouse have evaluated the situation, recalculated clearance rsquirements, and modified the bumper installation to allow for free thermal expansion and ceintain reactor coolant system qualification during all modes of operation. The unit is currently in Mode 3 continuing the post fuel load test program.

This information is current as of 10:00 a.m. (PDT) on July 25, 1985.

CONTACT: R. Dodds M. Mendonca FTS 463-3720 (805)'595-7500 DISTRIBUTION 11 St. +2lIl MNBB7 33 Phillips E/W 111ste Air Rights Mails Chairman Pa111dino EDO NRR IE NHSS ADMIDMB Ctam. Zech PA OIA RES DOT:Trans Only Comn.. Bernthal MPA AEOD Comm. Roberta ELD Comm. Asselstine Regions //~-l'Yf /?IT-J: NI f I8/~- 2 W/ 2/I'2P~I # V SECY INP07'06 NSAC 3/JL ACRS Licensee: 9'es-CA (Reactor Licensecs) REGION V: FORM 211 PDR Resident Inupector p 3 (Revised 3/14/83) 73 50 agoypy [" 0 PNO-V-BD-047 PDR

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